The inflammatory response is mediated primarily by leukocytes, neutrophils and lymphocytes, which circulate in the blood and reversibly interact with the vascular endothelium. In response to inflammatory stimuli, the leukocytes adhere tightly to the vascular endothelium, migrate (extravasate) through the vessel wall, and subsequently move along a chemotactic gradient toward the inflammatory stimulus. The interaction of leukocytes with vascular endothelial cells is thus an essential initial step in the inflammatory response. Selectins play a key role in inflammation, as they are responsible for the initial attachment of blood borne leukocytes to the vasculature. Preventing selectin-mediated cell adhesion can ameliorate or circumvent the deleterious consequences of inflammation. Therefore, selectins are the prime target for the therapy of cell-adhesion disorders, specifically for treatment of inflammation.
Selectins regulate neutrophil and lymphocyte adhesion to and entry into lymphoid tissues and sites of inflammation (Rosen, Am. J. Respir. Cell. Mol. Biol., 3:397-402, 1990). The three known selectins are E-selectin (formerly known as ELAM.1), P-selectin (formerly known as PADGEM, GMP-140, or CD61) and L-selectin (formerly known as mLHR, Leu8, TQ-1, gp90, MEL, Lam-1, or Lecam-1) (Lasky, Annu. Rev. Biochem. 64:113, 1995; Kansas, Blood 88:3259, 1996). Each selectin is regulated differently, and participates in a different manner in the process of inflammation or immunity. The lectin domains of each selectin are critical to the adhesive functions of the proteins. The selectins are responsible for leukocyte capture from the blood stream and mediate their intermittent attachment with consequent leukocyte “rolling” along the endothelial cell surface. This capture allows the cascade of secondary, tighter cell-adhesive events to take place. L-selectin is constitutively expressed by leukocytes and mediates lymphocyte adhesion to peripheral lymph node high endothelial venules, and neutrophil adhesion to cytokine-activated endothelial cells (Spertini et al. J. Immunol. 147:2565-2573, 1991). In inflammatory disorders it may be L-selectin that plays the most significant role (Shimizu et al., Immunol. Today 13:106, 1992; Picker et al., Annu. Rev. Immunol. 10:561, 1992).
Buerke et al. demonstrated the important role of selectins in inflammatory states such as ischemia-reperfusion injury in cats (Buerke, M. et al., J. Clin. Invest. 93:1140,1994). The presence of L-selectin and E- or P-selectin ligands on mononuclear cells has implicated these receptor-ligand interactions in chronic inflammation. (L. Lasky Annu. Rev. Biochem. 64:113-39, 1995). Monoclonal antibodies to L-selectin prevent neutrophil emigration into inflamed skin (Lewinsohn et al., J. Immunol. 138:4313, 1987), neutrophil and monocyte emigration into inflamed ascites (Jutila et al., J. Immunol. 143:3318, 1989), and neutrophil emigration into inflamed peritoneum. Jasin et al. provide support for the use of antibodies in inhibiting neutrophil accumulation in inflamed synovium (Jasin et al., Arthritis Rheum. 33:S34, 1990). Monoclonal antibody EL-246, directed against both L-selectin and E-selectin, attenuated sepsis-induced lung injury (Ridings, P C et al., Arch Surg. 1199-1208, 1995). Monoclonal antibody SMART is an L-selectin blocking antibody that is being used in clinical trials for trauma associated with multiple organ failure (this condition is believed to be due in part to infiltration of inflammatory cells). The anti-L-selectin antibody is presumed to provide its therapeutic effect by preventing neutrophil adhesion to endothelium and it is active in vivo in a primate model of severe trauma (Schlag G et al, Critical Care Medicine 1999, 27, 1900-1907). It is believed that this monoclonal antibody will be also useful in the treatment of adult respiratory distress syndrome and myocardial infarction.
Glycosaminoglycans (also referred to herein as “GAG” or “GAGs”) are naturally-occurring carbohydrate-based molecules implicated in the regulation of a number of cellular processes, including blood coagulation, angiogenesis, tumor growth, and smooth muscle cell proliferation, most likely by interaction with effector molecules. GAGs are often, but not always, found covalently bound to protein cores in structures called proteoglycans. Proteoglycan structures are abundant on cell surfaces and are associated with the extracellular matrix around cells. GAGs consist of repeating disaccharide units. For example, heparan sulfate glycosaminoglycans (also referred to herein as “HS-GAGs”) consist of repeating disaccharide units of D-glucuronic acid and N-acetyl- or N-sulfo-D-glucosamine. The high molecular diversity of HS-GAGs is due to their unique sulfation pattern (Sasisekharan, R. and Venkataraman, G., Current Opinion in Chem. Biol., 4, 626-631, 2000; Lindahl, U. et al., J. Biol. Chem., 273, 24979-24982, 1998; Esko, J. and Selleck, S. B., Annu. Rev. Biochem., 71, 435-471, 2002). One of the most thoroughly studied HS-GAGs is the widely used anticoagulant heparin. Heparin is a highly sulfated form of heparan sulfate found in mast cells. Many important regulatory proteins including cytokines, growth factors, enzymes, and cell adhesion molecules bind tightly to heparin. Although interactions of proteins with GAGs such as heparin and heparan sulfate are of great biological importance, the structural requirements for protein-GAG binding have not been well characterized. Ionic interactions are important in promoting protein-GAG binding and the spacing of the charged residues may determine protein-GAG affinity and specificity.
The HS-GAG paradigm provides new approaches and strategies for therapeutic intervention at the cell-tissue-organ interface. For example, identification of specific HS-GAG sequences that affect particular biological processes will enable the development of novel molecular therapeutics based on polysaccharide sequence. Synthetic HS-GAGs, or molecular mimics of HS-GAG sequences, may provide new approaches for combating health problems such as bacterial and viral infections, atherosclerosis, cancer, and Alzheimer's disease.
Selectins mediate their adhesive functions via lectin domains that bind to carbohydrate ligands. Emerging evidence indicates that GAGs, and in particular HS-GAGs, are carbohydrate receptors with which the selectins interact (Nelson R M, et al., Blood 82, 3253-3258, 1993; Ma, Y Q and Geng, J G, J. Immunol. 165, 558-565, 2000; Giuffre, L. et al., J. Cell. Biol. 136, 945-956, 1997; Watanabe N., et al., J. Biochem. 125, 826-831, 1999; Li Y F et al., FEBS Lett 444, 201-205, 1999). Consistent with this observation, heparin, HS-GAG and heparin-derived oligosaccharides block L-selectin-dependent adhesion directly (U.S. Pat. No. 5,527,785 to Bevilacqua et al.). Furthermore, short sulfated heparin-derived tetrasaccharides reduced binding of neutrophils to COS cells expressing P-selectin (Nelson R M, et al., Blood 82, 3253-3258, 1993). The multivalent nature of HS may be an important factor in binding L-selectin under flow conditions (Sanders et al, ibid).
As the interactions between GAGs and selectins play an important role in cell-matrix and cell-cell adhesion, the latter are processes involved in certain diseases and inflammatory disorders, modulating these interactions have therapeutic implications.
Bevilacqua et al (U.S. Pat. No. 5,527,785) provide a method of modulating selectin binding in a subject by administering heparin-like oligosaccharides. The oligosaccharides act by binding to L- or P-selectin.
Xie X et al (JBC 275, 34818-25, 2000) described inhibition of L- and P-selectin mediated cell adhesion by sulfated saccharides, including carboxyl-reduced and sulfated heparin. While these molecules have been useful to show the utility of selectin blockers for treating inflammation, each has significant drawbacks as a therapeutic, including short in vivo half-life, high cost, potential immunogenicity, and other possible side effects. A further limitation of these approaches is lack of efficient means to improve the pharmacological properties of these molecules.
In addition, several groups developed small peptides with high affinities for heparin or for heparin-like molecules (i.e., PGs, or other GAGs) (see, for example, U.S. Pat. No. 5,919,761 to Wakefield et al.) to use in a variety of applications for modulating the activities of native GAGs and PGs.
There is still an unmet need to have a non-peptide, small synthetic compounds, which are capable of modulating the functions of GAGs and the interactions between GAGs and GAG effector protein molecules.
U.S. Pat. No. 6,232,320 discloses the use of thieno[2,3-c]pyridines as inhibitors of cell adhesion useful as inhibitors of inflammation. The disclosed compounds are different from the compounds of the present invention as they posses a different heterocyclic system and do not posses sulfonylbenzoylamino group.
Japanese Patent Application JP 2001151779 discloses 4,5,6,7-tetrahydrothieno[2,3-c]pyridines, pharmaceutical compositions, and TNF-α formation inhibitors containing them, also disclosed in Fujita M, et al. (Bioorg. Med. Chem. Lett., 12: 1607-1611, 2002). A related Japanese Patent Application JP 2001151780 discloses novel 4,5,6,7-tetrahydrothieno[2,3-c]pyridines as inhibitors of TNF-alpha synthesis, also disclosed in Fujita et al. (Bioorg. Med. Chem. Lett. 12: 1897-1900, 2002). The two Japanese Patent Application provide different substituents in position 3 of the 4,5,6,7-tetrahdrothieno[2,3-c]pyridine ring (arylcarbonyl in the 2001151779 Application and carboxy or alkoxycarbonyl in the 2001151780 Application). All of these compounds, however, are different from those of the present invention as they do not contain a sulfonylbenzoylamino group as part of the scaffold, an essential feature of the compounds of the present invention.
Balakin et al. (J. Chem. Inf. Comput. Sci. 42: 1332-1342, 2002) describe in silico property-based design of a G-protein coupled receptor (GPCR)-targeted library of compounds. Among the tens of thousands of structures screened in silico, certain compounds from the GPCR-targeted library including a single thieno[2,3-c]pyridine compound were designated the highest scoring structures by the selection criteria applied in that analysis.
SciFinder Scholar database, release 2003, lists 2846 derivatives (as of Dec. 30, 2003) of thieno[2,3-c]pyridine, but no utility is attributed to any of these compounds and no chemical synthesis data are described.
Chemical Diversity Labs Inc. (San Diego, Calif.), a supplier of chemical compounds, released a database named CombiLab Probe Libraries (June 2002 revision; 220,674 compound structures), which lists 438 derivatives of thieno[2,3-c]pyridine, but no utility or chemical synthesis data is described.
I.F. Lab (Kiev, Ukraine), a supplier of chemical compounds, released a database named IF LAB Libraries (July 2003; 77,098 compound structures), which lists 3145 derivatives of thieno[2,3-c]pyridine, but no utility or chemical synthesis data is described. Some of the compounds in Chemical Diversity Labs Inc. database are the same as in I.F. LAB database.
Nowhere in the background art is it taught or suggested that sulfonylbenzoylamino derivatives of thieno[2,3-c]pyridines have beneficial pharmaceutical activities.